xsl/ical: properly prepend VALUE=DATE to dates without time as per RFC5545

xsl/ical.xsl

@@ -98,22 +98,31 @@
   <xsl:template match="end">
     <xsl:choose>
       <xsl:when test="not(string(.) = string(../start))">
+
+        <xsl:variable name="date">
+          <xsl:call-template name="date-to-hevent">
+            <xsl:with-param name="date">
+	      <xsl:choose>
+	        <xsl:when test="contains(., 'T')">
+	          <xsl:value-of select="string(.)"/>
+                </xsl:when>
+
+                <xsl:otherwise>
+	          <xsl:value-of select="date:add(., 'P1D')"/>
+                </xsl:otherwise>
+              </xsl:choose>
+            </xsl:with-param>
+          </xsl:call-template>
+        </xsl:variable>
+
 	<xsl:choose>
-	  <xsl:when test="contains(., 'T')">
+	  <xsl:when test="contains($date, 'T')">
             <xsl:text>DTEND:</xsl:text>
-            <xsl:call-template name="date-to-hevent">
-              <xsl:with-param name="date">
-	        <xsl:value-of select="string(.)"/>
-              </xsl:with-param>
-            </xsl:call-template>
+	    <xsl:value-of select="$date"/>
           </xsl:when>
           <xsl:otherwise>
             <xsl:text>DTEND;VALUE=DATE:</xsl:text>
-            <xsl:call-template name="date-to-hevent">
-              <xsl:with-param name="date">
-	        <xsl:value-of select="date:add(., 'P1D')"/>
-              </xsl:with-param>
-            </xsl:call-template>
+	    <xsl:value-of select="$date"/>
 	  </xsl:otherwise>
         </xsl:choose>